[clang] [Clang] Loop over FieldDecls instead of all Decls (PR #89453)

[Bill Wendling via cfe-commits]

https://github.com/bwendling created https://github.com/llvm/llvm-project/pull/89453

Only FieldDecls are of importance here. A struct defined within another struct has the same semantics as if it were defined outside of the struct. So there's no need to look into RecordDecls that aren't a field.

>From f6fe986fa23df709d502311d9db2e1b4de47bb67 Mon Sep 17 00:00:00 2001
From: Bill Wendling <morbo at google.com>
Date: Fri, 19 Apr 2024 13:45:38 -0700
Subject: [PATCH] [Clang] Loop over FieldDecls instead of all Decls

Only FieldDecls are of importance here. A struct defined within another
struct has the same semantics as if it were defined outside of the
struct. So there's no need to look into RecordDecls that aren't a field.
---
 clang/lib/CodeGen/CGBuiltin.cpp | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 4319501035e257..4ab844d206e48a 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -861,14 +861,13 @@ const FieldDecl *CodeGenFunction::FindFlexibleArrayMemberField(
 static unsigned CountCountedByAttrs(const RecordDecl *RD) {
   unsigned Num = 0;
 
-  for (const Decl *D : RD->decls()) {
-    if (const auto *FD = dyn_cast<FieldDecl>(D);
-        FD && FD->getType()->isCountAttributedType()) {
+  for (const FieldDecl *FD : RD->fields()) {
+    if (FD->getType()->isCountAttributedType())
       return ++Num;
-    }
 
-    if (const auto *Rec = dyn_cast<RecordDecl>(D))
-      Num += CountCountedByAttrs(Rec);
+    QualType Ty = FD->getType();
+    if (Ty->isRecordType())
+      Num += CountCountedByAttrs(Ty->getAsRecordDecl());
   }
 
   return Num;